1. Field of the Invention
The invention relates to vehicle bodies, and more particularly to load bearing floor constructions for vehicle bodies.
2. Reference to Prior Art
A known floor construction for a vehicle body, such as a trailer or shipping container, includes wooden floor boards supported on steel I-beams that span the width of the vehicle body. The I-beams reinforce the floor boards and are capable of supporting heavy loads including the loads encountered when a forklift is driven over the floor.
If the foregoing floor construction is to be insulated, sheets of metal or plywood are placed over the I-beams to form an underpan, and wood or metal stringers are placed on top of the sheets and directly over the I-beams to provide space for insulation between the underpan and the floor boards. The stringers relieve the insulation of carrying compressive loads, but are less thermally efficient than the insulation and therefore compromise the thermal performance of the vehicle body. Also, this floor construction is heavy and its assembly is time consuming and labor intensive.
Another known insulated floor construction is shown in U.S. Pat. No. 2,962,323 issued Nov. 29, 1962 to McBride. That patent illustrates a trailer including a floor made of interconnected floor panels that each have a STYROFOAM body which is sandwiched between fiberglass coverings and which carries a substantial portion of the compressive loads applied to the floor. The floor panels are bolted to a metal framework including metal stringers and crossmembers extending between lower rub rails on the trailer. Assembly of the floor in McBride is also time consuming and labor intensive and the bolt holes account for thermal leaks and provide sites for moisture penetration into the panels. The bolts also themselves act as "thermal shorts".
Another insulated floor construction is illustrated in U.S. Pat. No. 3,003,810 issued Oct. 10, 1961 to Kloote. That patent shows a floor constructed of interconnected panels each having a central core sandwiched between plywood sublaminae, the exposed faces of which are covered by structural skins. The cores of the panels must carry the entire compressive load applied to the floor and the sublaminae are subject to delamination from the core.